Self-propelled vehicle, in particular a road-building machine and a method for driving and controlling a vehicle with the aid of a rotatable driver seat

ABSTRACT

The inventive self-propelled vehicle, in particular a road-building machine, comprises a traction drive, a steering device and a rotatable driver seat ( 5 ) in which a traction drive control unit ( 6 ) is arranged. Adjustment signals for the traction drive are generated according to the direction of the adjustment of the control elements of said control unit ( 6 ). Said road-building machine also comprises a device for detecting the rotation angle μ of the instant rotating position of the seat and for correcting the directional components of the adjustment signals of the control elements to a −μ angle in such a way that the direction of the adjustment thereof corresponds to the direction of the vehicle motion at each rotating position of the seat.

BACKGROUND OF THE INVENTION

Self-propelled vehicle, in particular a road-building machine and amethod for driving and controlling a vehicle with the aid of a rotatabledriver seat

The invention refers to a self-propelled vehicle according to thepreamble of claim 1 and to a method according to the preamble of claim9.

Such vehicles that have a rotatable driver's seat are known, forexample, from road-building machines and in particular from roadrollers.

It is a requirement with road rollers to develop a driver's seat that isfreely rotatable around its vertical axis, since the operationalconditions of a roller require a continuous change of the seat positionof the operator relative to the travelling direction of the road roller.A prerequisite for a feasibility in terms of costs and functionality isthat the control elements rotate with the driver's seat. Otherwise, aplurality of redundant control elements would have to be used, whichwould be expensive. Typically, an asphalt roller, for example, worksbehind a paver that places the material and performs a pre-compaction.The roller travels several times over the surfaces laid by the paver toprovide the final compacting and the planarity of the surface. In doingso, the direction of travel is changed frequently—the number of forwardand backward travels is almost equal. To provide for or improve upon thevisibility of the working area, the security and the ergonomics of theoperation of the machine, it is necessary to rotate the driver's seat by180° every time the direction of travel is changed. Here, the roller maycab still on the hot asphalt only for the short duration taken by thechange of the travelling direction. Therefore and for reasons of time,the driver's seat should be rotated while driving. For respective shortdistances with different travelling directions, a seat position rotatedby 90° relative to the travelling direction is feasible. Depending onthe course to be travelled, seat positions between 0 and 90° relative tothe travelling direction may also be ergonomically feasible.

For a safe operation of the machines, the essential control elements,such as travelling direction transmitters (steering wheel, joystick) anddrive lever, for selecting the travelling direction and the speed mustbe associated with the travelling direction in a manner unambiguous tothe operator. Existing systems do not solve this problem. Accordingly, afree rotation of the driver's seat including the control elements whilethe roller travels—which is feasible in terms of applicationtechnology—was hereinbefore impossible.

EP 0935025 describes a system with a rotatable driver's seat, whereinthe driving operation is controlled dependent on the rotational positionof the driver's seat such that a control device reverses the directionof the drive presettings when the driver's seat is swivelled into apreset region. However, this reversal can only be effected with theroller at cabstill. Would the roller be travelling, rotating thedriver's seat could for instance cause a reversal of the travellingdirection of the roller that might not be intended by the driver.

From EP 0935023 A2, a method for a roller with two steerable drums thatcomprises a control device controlling the steering drive of both drumssuch that the respective front drum, seen in the travelling direction,is automatically controlled as the active drum through the steeringpresettings. Again, this method does not solve the problem of the senseof direction of the control elements when the seat position changesduring travel.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve a self-propelledvehicle with a rotatable driver's seat of the above mentioned type, aswell as a method for driving and steering a vehicle with a rotatabledriver's seat such that the association of the travelling direction ofthe control elements with the travelling direction of the vehicle ismaintained in any rotation angle position of the driver's seat.

The object is solved with the features of claim 1 and 9, respectively.

The invention advantageously provides that, in a control unit for thedriving operation which generates actuation signals for the drive andthe steering means in dependence on the direction of actuation of thecontrol elements of the control unit, a means detects the instantaneousrotation angle μ of the rotational position of the seat and corrects thedirection of the actuation signals of the control elements by an angle−μ such that the direction of actuation of the control elementscorresponds to the travelling direction of the vehicle in any rotationalposition of the seat.

The invention advantageously allows that the control elements of thecontrol unit always maintains a direction of actuation that correspondsto the travelling direction of the machine, even if the driver's seat isrotated during traction drive. Thus, the driver's seat is freelyrotatable during travel without having to interrupt the drivingoperation.

The means for detecting the instantaneous rotation angle of therotational seat position transmits the rotation angle mechanically,electro-mechanically, optically or electrically to the control unit.

Transmitting the rotation angle to the elements allows to correct theactuation signals generated by the control elements of the control unitby a value corresponding to the rotation angle of the driver's seat sothat a change of the rotational position of the seat has no influence onthe direction of actuation.

The direction of actuation of the control elements is thus always thesame and corresponds to the travelling direction of the vehicle.

In the control unit, the actuation signals for the selection of thetravelling direction and the steering are continuously corrected independence on the rotation angle of the instantaneous rotationalposition of the seat. The continuous correction of the direction of theactuation signals allows for a free optional rotation of the driver'sseat during travel.

The control unit comprises a single control lever for the selection ofthe travelling direction, the travelling speed and the steering.

The control lever is supported by a universal joint provided on aturnover that may be rotated by an angle −μ when the driver's seat takesa seat position under an angle of μ.

The transmission of the rotation angle to the control unit may beeffected, for example, using a flexible transmission shaft, anelectromotor drive or a torsion bar.

The housing of the control unit is preferably connected with thedriver's seat in a stationary manner.

The vehicle may have two steerable axes, the steering control beingadapted to switch the control lever to one of the two axes or to bothaxes.

Preferably, the control lever is guided in two mutually orthogonalslotted links.

The vehicle is a road-building machine, preferably a road roller.

The following is a detailed description of an embodiment of theinvention with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a road roller with a rotatable driver's seataccording to prior art.

FIG. 2 is a view similar to FIG. 1 with the travelling direction beingreversed.

FIG. 3 illustrates the actuation direction of the control leveraccording to the invention.

FIG. 4 shows the present control lever of the control unit.

FIGS. 5 and 6 illustrate different rotational positions of the driver'sseat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 schematically illustrate a road roller 1 with two rollerdrums 2, 3, at least one of which is steerable. The roller drums areinterconnected through a chassis 4 on which a driver's cab for anoperator is arranged.

The driver's cab is provided with a rotatable driver's seat 5 with anintegrated control unit for the drive operation. The control unit 6preferably comprises a control lever 8 whose functions will be detailedin connection with FIG. 4.

FIG. 1 illustrates a road roller 1 with at least one steerable drum 2.The drum steered is the front drum 2, seen in the travelling direction.In the left portion of the Figure, the position of the seat is alignedwith the travelling direction. In this case, turning the steering wheel7 to the left causes a change of the travelling direction towards theleft, the drive lever 9 is deflected in the travelling direction of theroad roller 1. When the driver's seat, including the control unit 6, isswivelled by 90° to the left or the right (middle portion of theFigure), it is already impossible to unambiguously associate thedirection of actuation at the control elements of the control unit tothe travelling direction. When the seat position is rotated by 180°while the travelling direction remains the same (right portion of theFigure), the direction of the actuation of the control elements does notcorrespond to the travelling direction. Consequently, the machine cannotbe operated safely.

FIG. 2 illustrates the same situation, but with the travelling directionchanged. Again, swivelling the driver's seat results in a loss ofassociation between the travelling direction of the road roller and therespective direction of actuation of the control elements drive lever 9and steering wheel 7.

FIG. 3 describes the solution underlying the invention, which integratesthe drive lever 9 and, preferably, the steering function in one controllever. In the case illustrated, the control lever 8 is deflected in thedirection of the arrow (20) and remains in this position—the machinetravels in the direction of the arrow. Moving the control lever 8 in thedirection of the arrow (18) causes a steering motion of the drum—themachine travels to the left. When the driver's seat is rotated by 90°during travel, the control lever 8 is tracked such that its sense ofdeflection still corresponds to the travelling direction. The directionof movement of the control lever 8 for steering corresponds to thedirection of movement of the road roller 1. The same is true for therotation of the driver's seat 5 by 180°. The driver's seat 5 may furtherbe rotated freely by more than 180°.

FIG. 4 illustrates the control unit 6 with its components, the controlfunctions and the device for transmitting the rotary motion of thedriver's seat 5 to the control unit. The control lever 8 comprisesswitching means 10 for the functions of lifting and lowering the edgepressing device, a switch means 12 for the rear wheel steering or dog'smovement, a switch means 14 for turning vibration on and off, a switchmeans 16 for unlocking the immobilizer, as well as a switch means 18with two degrees of freedom for the setting of the steering directionand a switch means 20 for the travelling direction. To make it easier onthe operator to differentiate between a steering motion and a travellingmotion during the deflection of the control lever, the steering motionis actuated against a spring force towards the neutral position and thetravelling deflection is actuated against a friction force. Preferably,the essential mentioned control functions are integrated in one controlunit 6. The housing 22 is fixedly connected to the driver's seat 5.Deflecting the control lever 8 in the direction of travel or steeringcauses a deflection of the respective slotted link (not illustrated inthe drawings) for the travelling or steering motion, respectively. Theslotted link for the travelling motion slides on the turnover 26 thatalso limits the outer position thereof. Shifted by 90°, the steeringmotion slides on the slotted link for the travelling motion. In theupper portion, the control lever 8 is guided by a universal joint 28. Inthe embodiment illustrated, the rotary motion of the driver's seat 5about its vertical axis is transmitted to the turnover 26 through aflexible shaft 30 acting as a transmission shaft. The rotary motion mayalso be transmitted by an electromotor or through a torsion bar.Swivelling the driver's seat 5 by an angle μ causes a turning of theturnover 26 in the housing 22 about an angle −μ (same value of therotation angle, but different sign). Together with the turnover 26, theslotted links for the travelling and the steering motion turn. Thus, theassociation of the direction of actuation of the control lever 8 withthe travelling direction of the road roller 1 is guaranteed.

The deflection of the control lever 8 for steering and travelling isdetected by two potentiometers 32 (direction x) and 34 (direction y) inthe universal joint 28 (pivot point of the control lever 8). A thirdpotentiometer 36 is mounted below the turnover 26 on the axis ofrotation thereof, measuring the rotation angle of the turnover 26relative to the housing 22 and thus the seat position. Thepotentiometers 32 and 34 are connected to the housing 22 in a mannersecured against rotation, i.e. swivelling the driver's seat 5 changesthe association of the respective potentiometer 32 and 34 to thedeflection of the drive lever. For example, in the initial position ofthe seat, the steering deflection of the control lever 8 is detected for100% by the potentiometer 34. Swivelling the driver's seat 5 causes achange of the position of the control lever 8 relative to thepotentiometers—i.e., the twisting of the universal joint 28 in its twoaxes changes. Corresponding to the rotation angle of the seat measuredby the rotation angle potentiometer, the steering deflection of thecontrol lever 8 is then sensed in part by both potentiometers 32, 24 inthe directions x and y. Since the rotation angle μ is known, theresulting signal can be calculated. The signal portion of thepotentiometers 32, 34 in the directions x and y, which changes with theswivelling of the seat, and the association of the control lever 8 tothe seat position is illustrated in FIGS. 5 and 6.

FIG. 5 schematically illustrates four different seat positions of theseat 5, shifted by 90° each, with the corresponding control unit 6. Foreach respective seat position, direction arrows illustrate in whichdirection the control lever 8 has to be moved for the functionsindicated. It is evident from the illustration that the direction ofactuation of the control lever 8 remains the same in all seat positions.

FIG. 6 also illustrates the direction of actuation of the control lever8, the arrow representing the direction for forward travel in all seatpositions.

1-9. (canceled)
 10. A self-propelled vehicle, in particular aroad-building machine, comprising: a driver's cab arranged on a chassis(4), a traction drive, a steering means, a rotatable driver's seat (5)provided in the driver's cab with an integrated control unit (6) for thedriving operation, which generates actuation signals for the tractiondrive and the steering means in dependence on the direction of actuationof control elements of the control unit (6), characterized in that meansdetect the instantaneous rotation angle μ of the rotational position ofthe seat and correct the direction components of the actuation signalsof the control elements by an angle −μ such that the direction ofactuation of the control elements corresponds to the direction ofmovement of the vehicle in any rotational position of the seat.
 11. Theself-propelled vehicle as defined in claim 10 wherein the means fordetecting the instantaneous rotation angle μ of the rotational positionof the seat transmits the rotation angle μ mechanically,electromechanically, optically or electrically to the control elementsof the control unit (6).
 12. The self-propelled vehicle as defined inclaim 10 wherein, in the control unit (6), the actuation signals for thetraveling direction and the steering may be continuously corrected independence on the rotation angle μ of the instantaneous rotationalposition of the seat.
 13. The self-propelled vehicle as defined in claim11 wherein, in the control unit (6), the actuation signals for thetraveling direction and the steering may be continuously corrected independence on the rotation angle μ of the instantaneous rotationalposition of the seat.
 14. The self-propelled vehicle as defined in claim10, wherein the control unit (6) comprises a single control lever (8) asthe control element for the selection of the traveling direction, thetraveling speed and the steering.
 15. The self-propelled vehicle asdefined in claim 11, wherein the control unit (6) comprises a singlecontrol lever (8) as the control element for the selection of thetraveling direction, the traveling speed and the steering.
 16. Theself-propelled vehicle as defined in claim 12, wherein the control unit(6) comprises a single control lever (8) as the control element for theselection of the traveling direction, the traveling speed and thesteering.
 17. The self-propelled vehicle as defined in claim 14 whereinthe control lever (8) is supported in a universal joint (28) and theuniversal joint (28) rests on a turnover (26) rotatable about a rotationangle −μ when the rotational position of the driver's seat (5) assumes arotation angle μ.
 18. The self-propelled vehicle as defined in claim 10wherein the vehicle has two steerable axes and wherein, at the controlunit (8), the steering control may be switched to one of both axes or toboth axes.
 19. The self-propelled vehicle as defined in claim 14 whereinthe control lever (8) is guided in two mutually orthogonal slotted links(24).
 20. The self-propelled vehicle as defined in claim 17 wherein thecontrol lever (8) is guided in two mutually orthogonal slotted links(24).
 21. The self-propelled vehicle as defined in claim 18 wherein thecontrol lever (8) is guided in two mutually orthogonal slotted links(24).
 22. The self-propelled vehicle as defined in claim 10 wherein thevehicle is a road roller (1).
 23. A method for driving and steering avehicle, in particular a road-building machine, with a rotatabledriver's seat (5) provided in a driver's cab and a control unit (6) forthe driving operation which is integrated in the driver's seat (5) andcomprises control elements, characterized by the detection of theinstantaneous rotation angle μ of the rotational position of the seatand the continuous correction of the actuation signals of the controlelements by an angle −μ, such that the direction of actuation of thecontrol elements corresponds to the direction of movement of the vehiclein any rotational position of the seat.